The present invention relates to a novel rotary disc loading mechanism by which compact discs (hereinafter referred to as CDs), video discs, records, or similar rotary discs of different outer diameters can each be loaded substantially vertically with its center set at a predetermined position.
The spread and growth of CDs in recent years are amazing and their sales volume has already exceeded that of LP records. Besides standard 12 cm diameter CDs (playing for 60 minutes each side), 8 cm diameter single CDs (playing for about 20 minutes each side) have recently been placed on the market.
FIG. 1 shows in section the principal part of a conventional CD loading mechanism adapted to load a CD for driving in an upright position. A lid 2 is pivotally secured to a disc housing of a CD player. In this example the lid 2 has its lower portion bent inwardly just about 90 degrees and extended to form a bottom 2a, the end portion of which has at either side a through hole 2b extending therethrough in parallel to the major surface of the lid 2. The lid 2 is hingedly fixed to a case 1 or the like of the CD player by means of bolts (not shown) inserted into the through holes 2b. The lid 2 has a circular cavity 2c centrally thereof, the bottom of which has a centrally-disposed circular hole 2d made therein coaxially with the cavity 2c and a circumferential marginal portion 2e surrounding the hole 2d.
A hollow cylindrical magnet 3 is disposed in the circular hole 2d. A CD holding disc 4 and a presser disc S are mounted on the inside and outside of the magnet 3, respectively, and they are coaxially assembled together by means of a screw 6. The CD holding disc 4 has an outer diameter a little larger than that of the circumferential marginal portion 2e. The central portion of the disc 4 is truncated-cone-shaped and juts out into the hollow cylindrical magnet 3. The outer diameter of the presser disc 5 is smaller than the inner diameter of the circular cavity 2c but larger than the diameter of the circular hole 2d. The magnet 3 and the discs 4 and 5 attached to the both sides thereof constitute a bobbin-shaped CD holding unit 7, which has an engaging recess 8 corresponding to a winding space, for engagement with the circumferential marginal portion 2e.
A square base plate 9, which has a circular hole 9a centrally thereof, is screwed onto the inside of the lid 2 with spacers held therebetween. The circular hole 9a has an inner diameter a little larger than the outer diameter of the circumferential marginal portion 2e and is held coaxially therewith. The base plate 9 has, centrally of its lower marginal edge, an inwardly projecting arc-shaped disc support 9b formed integrally therewith and coaxially with the circular hole 9a. The distance between the center of the circular hole 9a and the inner peripheral surface of the disc support 9b is equal to the 6 cm radius of the standard CD.
With this conventional CD loading mechanism, the standard type 12 cm diameter CD indicated by 11 is loaded in the following manner. After opening the lid 2 outwardly, the CD 11 needs only to be inserted into the opening so that it slides down along the inner surface of the CD holding disc 4. The CD 11 is automatically guided onto the disc support 9b and set at a pre-determined position.
Then, upon closing the lid 2, the disc holding unit 7 partly pops out toward a turntable 12 by virtue of the magnetic force acting between the magnet 3 and the turntable 12; so that a circular recess 4a of the CD holding disc 4 receives a trapezoidal portion 12a of the turntable 12 through a center hole 11a of the CD 11. At the same time, the CD 11 thus put on the turntable 12 rises just about 1.5 mm along its trapezoidal portion 12a, and consequently, the lower marginal edge of the CD 11 slightly moves up from the disc support 9b. In this way, the CD 11 is gripped between the CD holding disc 4 and the turntable 12.
On the other hand, an 8 cm diameter small sized CD must be set on a 12 cm diameter adapter 12 such as shown in FIGS. 2A and 2B, for loading into the above-mentioned CD loading mechanism. As shown in FIGS. 2A and 2B, the adapter 12 is an about 2 mm thick doughnut-shaped disc which is made of synthetic resin and has an 8 cm diameter hole 14a centrally thereof. The adapter 14 has notches 14b cut therein at equiangular intervals with respect to the center of the hole 14a and extending therefrom in its circumferential direction so that CD gripping portions 14c are defined between the notches 14b and the hole 14a. On the inner peripheral surface of the central hole 14a adjacent each CD gripping portion 14c there are protrusively provided a pair of parallel, opposed lugs 14d and 14e, which define therebetween a groove 14f for receiving the marginal edge of the CD. The lug 14d is less protrusive than the lug 14 e.
The small-sized CD is set on the adapter 14 in the following manner. The first step is to press the marginal portion of the CD into the grooves of two of the three gripping portions 14c from the side of the lugs 14d, followed by urging the CD toward the inner peripheral surface of the hole 14a intermediate between the two gripping portions 14c, by which the base portions of the two gripping portions 14c are elastically deformed and, at the same time, the notches 14b are narrowed. Then, by removing the force to the CD while holding the marginal portion of the CD opposite the remaining groove 14f of the remaining gripping portion 14c, the first two gripping portions 14c are restored to their initial state, pressing the marginal edge of the CD into the groove 14f of the remaining gripping portion 14c. Thus the small-sized CD is elastically gripped at its marginal edge by the three gripping portions 14c of the adapter 14.
As described above, according to the conventional CD loading mechanism, the small-sized CD cannot be set directly thereon and must be present on an adapter for loading in a CD player, which is very troublesome. Furthermore, the adapter utilizes the elasticity of its material (synthetic resin) for mounting, dismounting and holding of the small-sized CD, but a play is liable to occur between the adapter and the small-sized CD due to a decrease in the elasticity of the material by aging, a warp of the adapter surface and wear of the grooves 14f of the gripping portions, and consequently, the adapter is short-lived.